Multi-stage transmission for vehicle

ABSTRACT

A multi-stage transmission for a vehicle may include an input shaft, an output shaft, first, second, third and fourth planetary gear devices disposed between the input shaft and the output shaft to transmit rotary force, each of the first, second, third and fourth planetary gear devices having three rotary elements, and at least six shifting elements connected to the rotary elements of the planetary gear devices.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to Korean Patent Application No.10-2015-0029141, filed Mar. 2, 2015, the entire contents of which isincorporated herein for all purposes by this reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention generally relates to a multi-stage transmissionfor a vehicle and, more particularly, to a multi-stage transmissiontechnology able to realize as many shifting stages as possible using thefew parts and the simple configuration as far as possible, therebyimproving fuel efficiency of a vehicle.

Description of Related Art

Recent rising oil prices have driven worldwide car manufacturers intounlimited competition to improve fuel efficiency. In addition, greatefforts have been made to reduce the weight and improve the fuelefficiency of engines based on a variety of techniques such asdownsizing.

Meanwhile, among methods that can be sought for transmissions equippedin vehicles to improve fuel efficiency, there is a method allowing anengine to operate at more efficient operation points using themulti-staging of a transmission, thereby ultimately improving the fuelefficiency.

Further, such the multi-staging of a transmission allows an engine tooperate in a relatively low revolutions per minute (RPM) range, therebyfurther improving the quietness of a vehicle.

However, as the number of shifting stages of a transmission increases,the number of internal parts constituting the transmission alsoincreases. This may lead to undesirable effects instead, such as thereduced mountability and transfer efficiency and the increased cost andweight of the transmission. Therefore, in order to maximize the effectof improved fuel efficiency using the multi-staging of a transmission,it is important to devise a transmission structure able to realizemaximum efficiency using a relatively small number of parts and a simpleconfiguration.

The information disclosed in this Background of the Invention section isonly for enhancement of understanding of the general background of theinvention and should not be taken as an acknowledgement or any form ofsuggestion that this information forms the prior art already known to aperson skilled in the art.

BRIEF SUMMARY

Various aspects of the present invention are directed to providing amulti-stage transmission for a vehicle that is able to realize at leasteleven forward shifting stages and one reverse shifting stage with arelatively small number of parts and a simple configuration such that anengine may be operated at optimum operation points, thereby maximizingan improvement in the fuel efficiency of the vehicle, and the engine maybe operated more quietly, thereby improving the quietness of thevehicle.

According to various aspects of the present invention, a multi-stagetransmission for a vehicle may include an input shaft, an output shaft,first, second, third and fourth planetary gear devices disposed betweenthe input shaft and the output shaft to transmit rotary force, each ofthe first, second, third and fourth planetary gear devices having threerotary elements, and at least six shifting elements connected to therotary elements of the planetary gear devices, in which a first rotaryelement of the first planetary gear device may be selectively connectedto a third rotary element of the second planetary gear device anddisposed to be fixable by one shifting element of the at least sixshifting elements, a second rotary element of the first planetary geardevice may be continuously connected to the input shaft and selectivelyconnected to the third rotary element of the second planetary geardevice, and a third rotary element of the first planetary gear devicemay be continuously connected to a second rotary element of the secondplanetary gear device, in which a first rotary element of the secondplanetary gear device may be selectively connected to a second rotaryelement of the fourth planetary gear device, the second rotary elementof the second planetary gear device may be continuously connected to afirst rotary element of the fourth planetary gear device, and the thirdrotary element of the second planetary gear device may be continuouslyconnected to a first rotary element of the third planetary gear device,a second rotary element of the third planetary gear device may becontinuously connected to a third rotary element of the fourth planetarygear device and disposed to be fixable by another shifting element ofthe at least six shifting elements, and a third rotary element of thethird planetary gear device may be selectively connected to the secondrotary element of the fourth planetary gear device, and the secondrotary element of the fourth planetary gear device may be continuouslyconnected to the output shaft.

The first planetary gear device, the second planetary gear device, thethird planetary gear device and the fourth planetary gear device may besequentially arranged along an axial direction of the input shaft andthe output shaft.

The first rotary element of the first planetary gear device may bedisposed to be fixable to a transmission case by a fourth clutch fromamong the at least six shifting elements, the second rotary element ofthe third planetary gear device may be disposed to be fixable to thetransmission case by a fifth clutch from among the at least six shiftingelements, and remaining shifting elements from among the at least sixshifting elements may be configured to constitute selective connectionstructures between the rotary elements of the planetary gear devices.

A first clutch from among the at least six shifting elements may form aselective connection structure between the second rotary element of thefirst planetary gear device and the third rotary element of the secondplanetary gear device, a second clutch from among the at least sixshifting elements may form a selective connection structure between thefirst rotary element of the second planetary gear device and the secondrotary element of the fourth planetary gear device, a third clutch fromamong the at least six shifting elements may form a selective connectionstructure between the third rotary element of the third planetary geardevice and the second rotary element of the fourth planetary geardevice, and a sixth clutch from among the at least six shifting elementsmay form a selective connection structure between the first rotaryelement of the first planetary gear device and the third rotary elementof the second planetary gear device.

According to various aspects of the present invention, a multi-stagetransmission for a vehicle may include a first, second, third and fourthplanetary gear devices, each having three rotary elements, respectively,six shifting elements configured to selectively provide frictionalforce, and first, second, third, fourth, fifth, sixth, seventh, andeighth rotary shafts connected to the rotary elements of the first tofourth planetary gear devices, in which the first rotary shaft may bethe input shaft directly connected to a second rotary element of thefirst planetary gear device, the second rotary shaft may be directlyconnected to a first rotary element of the first planetary gear device,the third rotary shaft may be directly connected to a third rotaryelement of the first planetary gear device, a second rotary element ofthe second planetary gear device and a first rotary element of thefourth planetary gear device, the fourth rotary shaft may be directlyconnected to a third rotary element of the second planetary gear deviceand a first rotary element of the third planetary gear device, the fifthrotary shaft may be directly connected to a first rotary element of thesecond planetary gear device, the sixth rotary shaft may be directlyconnected to a second rotary element of the third planetary gear deviceand a third rotary element of the fourth planetary gear device, theseventh rotary shaft may be directly connected to a third rotary elementof the third planetary gear device, and the eighth rotary shaft may bethe output shaft directly connected to a second rotary element of thefourth planetary gear device, and the six shifting elements may includefirst, second, third, fourth, fifth, and sixth clutches, the firstclutch may be disposed between the first rotary shaft and the fourthrotary shaft, the second clutch may be disposed between the fifth rotaryshaft and the eighth rotary shaft, the third clutch may be disposedbetween the seventh rotary shaft and the eighth rotary shaft, the fourthclutch may be disposed between the second rotary shaft and atransmission case, the fifth clutch may be disposed between the sixthrotary shaft and the transmission case, and the sixth clutch may bedisposed between the second rotary shaft and the fourth rotary shaft.

According to the present invention as set forth above, the multi-stagetransmission for a vehicle can realize at least eleven forward shiftingstages and one reverse shifting stage with a relatively small number ofparts and a simple configuration such that the engine may be operated atoptimum operation points, thereby maximizing an improvement in the fuelefficiency of the vehicle, and the engine may be operated more quietly,thereby improving the quietness of the vehicle.

It is understood that the term “vehicle” or “vehicular” or other similarterms as used herein is inclusive of motor vehicles in general such aspassenger automobiles including sports utility vehicles (SUV), buses,trucks, various commercial vehicles, watercraft including a variety ofboats and ships, aircraft, and the like, and includes hybrid vehicles,electric vehicles, plug-in hybrid electric vehicles, hydrogen-poweredvehicles and other alternative fuel vehicles (e.g., fuel derived fromresources other than petroleum). As referred to herein, a hybrid vehicleis a vehicle that has two or more sources of power, for example, bothgasoline-powered and electric-powered vehicles.

The methods and apparatuses of the present invention have other featuresand advantages which will be apparent from or are set forth in moredetail in the accompanying drawings, which are incorporated herein, andthe following Detailed Description, which together serve to explaincertain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a configuration of an exemplarymulti-stage transmission for a vehicle according to the presentinvention.

FIG. 2 illustrates an operation mode table of the exemplary transmissionshown in FIG. 1.

It should be understood that the appended drawings are not necessarilyto scale, presenting a somewhat simplified representation of variousfeatures illustrative of the basic principles of the invention. Thespecific design features of the present invention as disclosed herein,including, for example, specific dimensions, orientations, locations,and shapes will be determined in part by the particular intendedapplication and use environment.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of thepresent invention(s), examples of which are illustrated in theaccompanying drawings and described below. While the invention(s) willbe described in conjunction with exemplary embodiments, it will beunderstood that the present description is not intended to limit theinvention(s) to those exemplary embodiments. On the contrary, theinvention(s) is/are intended to cover not only the exemplaryembodiments, but also various alternatives, modifications, equivalentsand other embodiments, which may be included within the spirit and scopeof the invention as defined by the appended claims.

Referring to FIG. 1 and FIG. 2, a multi-stage transmission for a vehicleaccording to various embodiments of the present invention may include aninput shaft IN; an output shaft OUT; a first to fourth planetary geardevices PG1, PG2, PG3 and PG4 disposed between the input shaft IN andthe output shaft OUT to transmit rotary force, each of the first tofourth planetary gear devices PG1 to PG4 having three rotary elements;and at least six shifting elements connected to rotary elements of thefirst to fourth planetary gear devices PG1 to PG4.

A first rotary element S1 of the first planetary gear device PG1 may beselectively connected to a third rotary element R2 of the secondplanetary gear device PG2 and installed to be fixable by one shiftingelement of the at least six shifting elements. A second rotary elementC1 of the first planetary gear device PG1 may be continuously connectedto the input shaft IN and selectively connected to the third rotaryelement R2 of the second planetary gear device PG2. A third rotaryelement R1 of the first planetary gear device PG1 may be continuouslyconnected to a second rotary element C2 of the second planetary geardevice PG2.

The first rotary element S2 of the second planetary gear device PG2 maybe selectively connected to a second rotary element C4 of the fourthplanetary gear device PG4, a second rotary element C2 of the secondplanetary gear device PG2 may be continuously connected to a firstrotary element S4 of the fourth planetary gear device PG4, and a thirdrotary element R2 of the second planetary gear device PG2 may becontinuously connected to a first rotary element S3 of the thirdplanetary gear device PG3.

A second rotary element C3 of the third planetary gear device PG3 may becontinuously connected to a third rotary element R4 of the fourthplanetary gear device PG4 and installed to be fixable by anothershifting element of the at least six shifting elements, and a thirdrotary element R3 of the third planetary gear device PG3 may beconnected to the second rotary element C4 of the fourth planetary geardevice PG4.

The second rotary element C4 of the fourth planetary gear device PG4 maybe continuously connected to the output shaft OUT.

The first planetary gear device PG1, the second planetary gear devicePG2, the third planetary gear device PG3 and the fourth planetary geardevice PG4 may be sequentially arranged along the axial direction of theinput shaft IN and the output shaft OUT.

The first rotary element S1 of the first planetary gear device PG1 maybe installed to be fixable to a transmission case CS by means of afourth clutch CL4 from among the at least six shifting elements. Thesecond rotary element C3 of the third planetary gear device PG3 may beinstalled to be fixable to the transmission case CS by means of a fifthclutch CL5 from among the at least six shifting elements.

Therefore, the fourth clutch CL4, the fifth clutch CL5 function asbrakes, respectively, such that the first rotary element S1 of the firstplanetary gear device PG1 and the second rotary element C3 of the thirdplanetary gear device PG3 may be converted to rotatable state orrestrained state not to be rotated by means of the operations of thefourth clutch CL4 and the fifth clutch CL5, respectively.

The other shifting elements from among the at least six shiftingelements may be configured to constitute selective connection structuresbetween the rotary elements of the planetary gear devices.

That is, the first clutch CL1 from among the at least six shiftingelements may form a selective connection structure between the secondrotary element C1 of the first planetary gear device PG1 and the thirdrotary element R2 of the second planetary gear device PG2. The secondclutch CL2 from among the at least six shifting elements may form aselective connection structure between the first rotary element S2 ofthe second planetary gear device PG2 and the second rotary element C4 ofthe fourth planetary gear device PG4. The third clutch CL3 from amongthe at least six shifting elements may form a selective connectionstructure between the third rotary element R3 of the third planetarygear device PG3 and the second rotary element C4 of the fourth planetarygear device PG4. The sixth clutch CL6 from among the at least sixshifting elements may form a selective connection structure between thefirst rotary element S1 of the first planetary gear device PG1 and thethird rotary element R2 of the second planetary gear device PG2.

In various embodiments, the first rotary element S1, the second rotaryelement C1 and the third rotary element R1 of the first planetary geardevice PG1 are a first sun gear, a first carrier and a first ring gear,respectively. The first rotary element S2, the second rotary element C2and the third rotary element R2 of the second planetary gear device PG2are a second sun gear, a second carrier and a second ring gear,respectively. The first rotary element S3, the second rotary element C3and the third rotary element R3 of the third planetary gear device PG3are a third sun gear, a third carrier and a third ring gear,respectively. The first rotary element S4, the second rotary element C4and the third rotary element R4 of the fourth planetary gear device PG4are a fourth sun gear, a fourth carrier and a fourth ring gear,respectively.

The multi-stage transmission for a vehicle configured as above may alsobe presented as follows.

Specifically, the multi-stage transmission for a vehicle according tothe present invention may include the first to fourth planetary geardevices PG1 to PG4 each having the three rotary elements; the sixshifting elements configured to selectively provide frictional force;and eight rotary shafts connected to the rotary elements of the first tofourth planetary gear devices.

Hence, from among the eight rotary shafts, the first rotary shaft RS1may be the input shaft IN directly connected to the second rotaryelement C1 of the first planetary gear device PG1. The second rotaryshaft RS2 may be directly connected to the first rotary element S1 ofthe first planetary gear device PG1. The third rotary shaft RS3 may bedirectly connected to the third rotary element R1 of the first planetarygear device PG1, the second rotary element C2 of the second planetarygear device PG2 and the first rotary element S4 of the fourth planetarygear device PG4. The fourth rotary shaft RS4 may be directly connectedto the third rotary element R2 of the second planetary gear device PG2,the first rotary element S3 of the third planetary gear device PG3. Thefifth rotary shaft RS5 may be directly connected to the first rotaryelement S2 of the second planetary gear device PG2. The sixth rotaryshaft RS6 may be directly connected to the second rotary element C3 ofthe third planetary gear device PG3 and the third rotary element R4 ofthe fourth planetary gear device PG4. The seventh rotary shaft RS7 maybe directly connected to the third rotary element R3 of the thirdplanetary gear device PG3. The eighth rotary shaft RS8 may be the outputshaft OUT directly connected to the second rotary element C4 of thefourth planetary gear device PG4.

In addition, from among the six shifting elements, the first clutch CL1may be disposed between the first rotary shaft RS1 and the fourth rotaryshaft RS4. The second clutch CL2 may be disposed between the fifthrotary shaft RS5 and the eighth rotary shaft RS8. The third clutch CL3may be disposed between the seventh rotary shaft RS7 and the eighthrotary shaft RS8. The fourth clutch CL4 may be disposed between thesecond rotary shaft RS2 and the transmission case CS. The fifth clutchCL5 may be disposed between the sixth rotary shaft RS6 and thetransmission case CS. The sixth clutch CL6 may be disposed between thesecond rotary shaft RS2 and the fourth rotary shaft RS4.

As set forth above, the multi-stage transmission for a vehicle accordingto the present invention including the four simple planetary geardevices and the six shifting elements realizes eleven forward shiftingstages and one reverse shifting stage according to the operation modetable as illustrated in FIG. 2. Since the multi-stage shifting stages ofeleven shifting stages can be embodied based on a relatively smallnumber of parts and a simple configuration, the multi-stage transmissionfor a vehicle can contribute to the improved fuel efficiency andquietness of a vehicle, thereby ultimately improving the marketabilityof the vehicle.

The foregoing descriptions of specific exemplary embodiments of thepresent invention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteachings. The exemplary embodiments were chosen and described in orderto explain certain principles of the invention and their practicalapplication, to thereby enable others skilled in the art to make andutilize various exemplary embodiments of the present invention, as wellas various alternatives and modifications thereof. It is intended thatthe scope of the invention be defined by the Claims appended hereto andtheir equivalents.

What is claimed is:
 1. A multi-stage transmission for a vehicle,comprising: an input shaft; an output shaft; first, second, third andfourth planetary gear devices disposed between the input shaft and theoutput shaft to transmit rotary force, each of the first, second, thirdand fourth planetary gear devices having three rotary elements; and atleast six shifting elements connected to the rotary elements of theplanetary gear devices, wherein a first rotary element of the firstplanetary gear device is selectively connected to a third rotary elementof the second planetary gear device and disposed to be fixable by oneshifting element of the at least six shifting elements, a second rotaryelement of the first planetary gear device is continuously connected tothe input shaft and selectively connected to the third rotary element ofthe second planetary gear device, and a third rotary element of thefirst planetary gear device is continuously connected to a second rotaryelement of the second planetary gear device, wherein a first rotaryelement of the second planetary gear device is selectively connected toa second rotary element of the fourth planetary gear device, the secondrotary element of the second planetary gear device is continuouslyconnected to a first rotary element of the fourth planetary gear device,and the third rotary element of the second planetary gear device iscontinuously connected to a first rotary element of the third planetarygear device, wherein a second rotary element of the third planetary geardevice is continuously connected to a third rotary element of the fourthplanetary gear device and disposed to be fixable by another shiftingelement of the at least six shifting elements, and a third rotaryelement of the third planetary gear device is selectively connected tothe second rotary element of the fourth planetary gear device, andwherein the second rotary element of the fourth planetary gear device iscontinuously connected to the output shaft.
 2. The multi-stagetransmission according to claim 1, wherein the first planetary geardevice, the second planetary gear device, the third planetary geardevice and the fourth planetary gear device are sequentially arrangedalong an axial direction of the input shaft and the output shaft.
 3. Themulti-stage transmission according to claim 2, wherein: the first rotaryelement of the first planetary gear device is disposed to be fixable toa transmission case by a fourth clutch from among the at least sixshifting elements, the second rotary element of the third planetary geardevice is disposed to be fixable to the transmission case by a fifthclutch from among the at least six shifting elements, and remainingshifting elements from among the at least six shifting elements areconfigured to constitute selective connection structures between therotary elements of the planetary gear devices.
 4. The multi-stagetransmission according to claim 3, wherein: a first clutch from amongthe at least six shifting elements forms a selective connectionstructure between the second rotary element of the first planetary geardevice and the third rotary element of the second planetary gear device,a second clutch from among the at least six shifting elements forms aselective connection structure between the first rotary element of thesecond planetary gear device and the second rotary element of the fourthplanetary gear device, a third clutch from among the at least sixshifting elements forms a selective connection structure between thethird rotary element of the third planetary gear device and the secondrotary element of the fourth planetary gear device, and a sixth clutchfrom among the at least six shifting elements forms a selectiveconnection structure between the first rotary element of the firstplanetary gear device and the third rotary element of the secondplanetary gear device.
 5. A multi-stage transmission for a vehicle,comprising: a first, second, third and fourth planetary gear devices,each having three rotary elements, respectively; six shifting elementsconfigured to selectively provide frictional force; and first, second,third, fourth, fifth, sixth, seventh, and eighth rotary shafts connectedto the rotary elements of the first to fourth planetary gear devices,wherein the first rotary shaft is the input shaft directly connected toa second rotary element of the first planetary gear device, the secondrotary shaft is directly connected to a first rotary element of thefirst planetary gear device, the third rotary shaft is directlyconnected to a third rotary element of the first planetary gear device,a second rotary element of the second planetary gear device and a firstrotary element of the fourth planetary gear device, the fourth rotaryshaft is directly connected to a third rotary element of the secondplanetary gear device and a first rotary element of the third planetarygear device, the fifth rotary shaft is directly connected to a firstrotary element of the second planetary gear device, the sixth rotaryshaft is directly connected to a second rotary element of the thirdplanetary gear device and a third rotary element of the fourth planetarygear device, the seventh rotary shaft is directly connected to a thirdrotary element of the third planetary gear device, and the eighth rotaryshaft is the output shaft directly connected to a second rotary elementof the fourth planetary gear device, and wherein the six shiftingelements include a first, second, third, fourth, fifth, and sixthclutches, the first clutch is disposed between the first rotary shaftand the fourth rotary shaft, the second clutch is disposed between thefifth rotary shaft and the eighth rotary shaft, the third clutch isdisposed between the seventh rotary shaft and the eighth rotary shaft,the fourth clutch is disposed between the second rotary shaft and atransmission case, the fifth clutch is disposed between the sixth rotaryshaft and the transmission case, and the sixth clutch is disposedbetween the second rotary shaft and the fourth rotary shaft.
 6. Themulti-stage transmission according to claim 5, wherein the firstplanetary gear device, the second planetary gear device, the thirdplanetary gear device and the fourth planetary gear device aresequentially arranged along an axial direction of the input shaft andthe output shaft.
 7. The multi-stage transmission according to claim 5,wherein: a first clutch from among the at least six shifting elementsforms a selective connection structure between the second rotary elementof the first planetary gear device and the third rotary element of thesecond planetary gear device, a second clutch from among the at leastsix shifting elements forms a selective connection structure between thefirst rotary element of the second planetary gear device and the secondrotary element of the fourth planetary gear device, a third clutch fromamong the at least six shifting elements forms a selective connectionstructure between the third rotary element of the third planetary geardevice and the second rotary element of the fourth planetary geardevice, and a sixth clutch from among the at least six shifting elementsforms a selective connection structure between the first rotary elementof the first planetary gear device and the third rotary element of thesecond planetary gear device.